nitrogen assimilation

Question

Nitrate is reduced to nitrite in plants by which enzyme?

RankGuru · Accepted Answer

1. **Nitrogen Uptake**: Plants usually absorb nitrogen from the soil in the form of nitrate ($NO_3^-$).
2. **Two-Step Reduction**: Before it can be used for amino acid synthesis, nitrate must be reduced to ammonium.
   - **Step 1**: $NO_3^-$ is reduced to **Nitrite ($NO_2^-$)** in the cytoplasm. This is catalyzed by the enzyme **Nitrate Reductase**.
   - **Step 2**: Nitrite is then transported into chloroplasts/plastids and reduced to Ammonium ($NH_4^+$) by **Nitrite Reductase**.
3. **Others**: Nitrogenase is for fixation of atmospheric $N_2$ (in bacteria); Glutamine synthase incorporates $NH_4^+$ into amino acids.

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nitrogen assimilation

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